Messages in this thread | | | Subject | Re: [PATCH] USB:Fix ehci infinite suspend-resume loop issue in zhaoxin | From | "" <> | Date | Wed, 16 Mar 2022 10:18:39 +0800 |
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On 2022/3/15 11:18, Alan Stern wrote: > On Tue, Mar 15, 2022 at 08:39:09PM +0800, WeitaoWang-oc@zhaoxin.com wrote: >> On 2022/3/14 10:24, Alan Stern wrote: >>>> + t1 = ehci_readl(ehci, &ehci->regs->status); >>>> + ehci_writel(ehci, t1 & STS_PCD, &ehci->regs->status); >>>> + ehci_readl(ehci, &ehci->regs->status); >>> >>> You should not clear the STS_PCD bit. What if some other port had a >>> status change at the same time? Then because you cleared the >>> port-change-detect bit, the system would not realize that the other port >>> needed to be handled. >> >> I really didn't think about this case. >> >>> Leaving the STS_PCD bit turned on will cause the driver to do a little >>> extra work, but it shouldn't cause any harm. >>> >> I have encountered the following situation if EHCI runtime suspend is >> enabled by default. >> >> >> >> 1.Wake from system to disk and boot OS. > > You're talking about resuming after hibernation, right?
You're right. >> 2.EHCI will entry runtime suspend after enumerated by driver during boot >> phase of suspend to disk > > I'm not sure what you mean by "boot phase of suspend to disk". This is > while the restore kernel is starting up at the beginning of resume from > hibernation, right? > You understood exactly what I was saying.
>> 3.EHCI will be placed to freeze state and ehci_resume is called after image >> is loaded. > > ehci_resume is called to leave runtime suspend. Going into the freeze > state doesn't require any changes. > >> 4.If PCD flag is set(caused by patch), then HCD_FLAG_RH_RUNNING will be set. >> >> 5.Pci_pm_freeze_noirq is called to check ehci root hub state and return >> value is -EBUSY. which will cause >> quiesce phase of suspend to disk fail. > > You're talking about check_root_hub_suspended() in hcd-pci.c, right? > It's right. > You know, I'm not at all certain that the callbacks for freeze and > freeze_noirq should ever return anything other than 0. It's okay for > them to call check_root_hub_suspended(), but they should ignore its > return value. > > Can you check if the patch below helps? > > Alan Stern > > > Index: usb-devel/drivers/usb/core/hcd-pci.c > =================================================================== > --- usb-devel.orig/drivers/usb/core/hcd-pci.c > +++ usb-devel/drivers/usb/core/hcd-pci.c > @@ -575,6 +575,12 @@ static int hcd_pci_resume(struct device > return resume_common(dev, PM_EVENT_RESUME); > } > > +static int hcd_pci_freeze_check(struct device *dev) > +{ > + (void) check_root_hub_suspended(dev); > + return 0; > +} > + > static int hcd_pci_restore(struct device *dev) > { > return resume_common(dev, PM_EVENT_RESTORE); > @@ -586,6 +592,7 @@ static int hcd_pci_restore(struct device > #define hcd_pci_suspend_noirq NULL > #define hcd_pci_resume_noirq NULL > #define hcd_pci_resume NULL > +#define hcd_pci_freeze_check NULL > #define hcd_pci_restore NULL > > #endif /* CONFIG_PM_SLEEP */ > @@ -616,8 +623,8 @@ const struct dev_pm_ops usb_hcd_pci_pm_o > .suspend_noirq = hcd_pci_suspend_noirq, > .resume_noirq = hcd_pci_resume_noirq, > .resume = hcd_pci_resume, > - .freeze = check_root_hub_suspended, > - .freeze_noirq = check_root_hub_suspended, > + .freeze = hcd_pci_freeze_check, > + .freeze_noirq = hcd_pci_freeze_check,
This patch can fix pci driver's fail check in freeze_noirq phase.
Restoring system state from a hibernation image can continue and success.
Weitao Wang > .thaw_noirq = NULL, > .thaw = NULL, > .poweroff = hcd_pci_suspend, > . >
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